Tetana, Brunner von Wattenwyl, 1878

Perkins, Philip D., 2011, New species (130) of the hyperdiverse aquatic beetle genus Hydraena Kugelann from Papua New Guinea, and a preliminary analysis of areas of endemism (Coleoptera: Hydraenidae) 2944, Zootaxa 2944 (1), pp. 1-417 : 48-49

Tetana group

Ten species are included in the Tetana group. These are generally very darkly colored species, dorsum piceous, except two species that have a pronotal fascia ( H. biundulata and H. penultimata ) ( Figs. 66 , 67 , 70 , 71 , 74 , 75 , 78 , 79 , 82 , 83 ). Males of four of the species are immediately recognized by a prominent midventral tubercle on the first abdominal ventrite (e.g., Fig. 305 ); these species are H. tetana , H. insandalia , H. acumena , and H. aulaarta . Males of three other species have a different abdominal sexual dimorphism: the fifth ventrite is raised in a transverse ridge, abruptly declivous behind; species with this character are H. tarsotricha , H. tricosipes , and H. huonica . The meso- and metatibiae are not markedly modified, but seven of the species have long hair-like setae on the tarsi of those legs (e.g., Fig. 314 ).

Most of the species have very large plaques that are very narrowly separated, more narrowly separated posteriorly than anteriorly, which is unusual in the genus (e.g., Figs. 308, 309 , 311 ). The pronotal foveae are reduced in all but two species: PF1 and PF4 are absent, and PF2 is extremely shallow, obsolete. Several of the species are very similar in most characters, and will require examination of the male genitalia for reliable determinations.

A characteristic feature of the aedeagus in this group is the shape of the left paramere, which is usually moreor-less oval in cross-section, very strong and stiff, and arches up and over the distal piece (e.g., Figs. 68, 69). Two species, H. penultimata and H. altapapua , have plaques shaped differently than the other species ( Figs. 78 , 83 ), and also have quite distinct male genitalia ( Figs. 80 , 85 ); these two species, however, have the characteristic arching left paramere and are therefore provisionally placed in the Tetana group. The female tergite X, gonocoxite, and spermatheca of H. tetana , H. tarsotricha , and H. biundulata are illustrated ( Figs. 395–397); they are quite similar, with (as in the male genitalia) H. biundulata being slightly different from the other two species.

Members of this group have been collected at an elevation range of 500–2680 m. Seven of the ten species have not been collected above 1700 m; the three other species have been collected at a range of 970–2680 m (maps Figs. 459–468 ). The distributions suggest that this is primarily an Area 1 group, with some species spreading to the Finisterre Mts. (Area 5) and the Herzog Mts. (Area 6); only one of the ten species in the group, H. huonica , is endemic to Area 5, and no species is endemic to Area 6. Most microhabitat data indicate gravel banks of streams or rivers, with a few pools or ponds mentioned. Representative microhabitat notations include the following: washed from margins of riverside still water pools in rainforest, gravel and cobble dominated microhabitats, but some muddy; muddy gravel banks of small shaded stream; gravel bank of small river in places where rotten leaves had accumulated; washed from margins of small pool of a steep, rocky, forest stream at confluence with river, gravel, cobbles, wet rock microhabitats; gravel banks of small clear river in dense forest; montane stream tumbled down among moss-covered rocks which alternated with short sandy runs in more level sections, almost completely shaded.

Figures

FIGURE 66. Hydraena tetana, holotype, dorsal and lateral habitus, and venter.

FIGURE 67. Hydraena tarsotricha, holotype, dorsal and lateral habitus, and venter.

FIGURE 70. Hydraena tricosipes, holotype, dorsal and lateral habitus, and venter.

FIGURE 71. Hydraena huonica, holotype, dorsal and lateral habitus, and venter.

FIGURE 74. Hydraena insandalia, holotype, dorsal and lateral habitus, and venter.

FIGURE 75. Hydraena biundulata, holotype, dorsal and lateral habitus, and venter.

FIGURE 78. Hydraena penultimata, holotype, dorsal and lateral habitus, and venter.

FIGURE 79. Hydraena acumena, holotype, dorsal and lateral habitus, and venter.

FIGURE 82. Hydraena aulaarta, holotype, dorsal and lateral habitus, and venter.

FIGURE 83. Hydraena altapapua, holotype, dorsal and lateral habitus, and venter.

FIGURES 304–309. Scanning electron micrographs of H. tetana (304–307) and H. tarsotricha (308–309).

FIGURES 310–315. Scanning electron micrographs of H. tricosipes (310–313) and H. tarsotricha (314–315).

FIGURES 80–81. Aedeagi of holotypes. 80. H. penultimata. 81. H. acumena.

FIGURES 84–85. Aedeagi of holotypes. 84. H. aulaarta. 85. H. altapapua.

FIGURES 459–462. Geographical distributions of Hydraena species.

FIGURES 463–466. Geographical distributions of Hydraena species.

FIGURES 467–470. Geographical distributions of Hydraena species.